Validation of ICD-10-AM Coding for Myocardial Infarction Subtype in Hospitalisation Data

Lee Nedkoff; Derrick Lopez; Joseph Hung; Matthew Knuiman; Tom G Briffa; Kevin Murray; Esther Davis; Soleiman Aria; Keira Robinson; John Beilby; Michael S T Hobbs; Frank M Sanfilippo

doi:10.1016/j.hlc.2021.11.014

Validation of ICD-10-AM Coding for Myocardial Infarction Subtype in Hospitalisation Data

Heart Lung Circ. 2022 Jun;31(6):849-858. doi: 10.1016/j.hlc.2021.11.014. Epub 2022 Jan 20.

Authors

Affiliations

¹ School of Population and Global Health, The University of Western Australia, Perth, WA, Australia. Electronic address: lee.nedkoff@uwa.edu.au.
² School of Population and Global Health, The University of Western Australia, Perth, WA, Australia.
³ Medical School, The University of Western Australia, Perth, WA, Australia.
⁴ Department of Cardiology, Sir Charles Gairdner Hospital, Perth, WA, Australia.
⁵ Department of Cardiology, Royal Perth Hospital, Perth, WA, Australia.
⁶ PathWest Laboratory Medicine of Western Australia, Perth, WA, Australia; School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia.

PMID: 35065895
DOI: 10.1016/j.hlc.2021.11.014

Abstract

Background: International Classification of Disease (ICD) codes are central for identifying myocardial infarction (MI) in administrative hospitalisation data, however validation of MI subtype codes is limited. We measured the sensitivity and specificity of ICD-10-AM (Australian Modification) codes for ST-elevation MI (STEMI) and non-STEMI (NSTEMI).

Methods: A sample of MI admissions was obtained from a dataset containing all MI hospitalisations in Western Australia (WA) for 2003, 2008 and 2013. Clinical data were collected from hospital medical records (n=799 patients). Cases were classified by ICD-10-AM codes for STEMI, NSTEMI and unspecified MI, and compared to clinical classification from review of available electrocardiographs (ECGs) and cardiac biomarkers (n=660). Sensitivity and specificity for ICD-10-AM coding versus clinical classification was measured, stratified by calendar year of discharge.

Results: The majority of classifiable cases had MI recorded in the principal diagnosis field (STEMI n=293, 84.2%; NSTEMI n=202, 74.3%; unspecified MI n=20, 50.0%). Overall sensitivity of the ICD-10-AM STEMI code was 86.3% (95% CI 81.7-90.0%) and was higher when restricted to MI as a principal versus secondary diagnosis (88.8% vs 66.7%). Comparable values for NSTEMI were 66.7% (95% CI 61.5-71.6%), and 68.8% vs 61.4% respectively. Between 2003 and 2013, sensitivity for both MI subtypes increased: 80.2-89.5% for STEMI, and 51.2-73.8% for NSTEMI. Specificity was high for NSTEMI throughout (88.2% 95% CI 84.1-91.6%), although improving over time for STEMI (68.1-76.4%).

Conclusions: The sensitivity and specificity of ICD-10-AM codes for MI subtypes in hospitalisation data are generally high, particularly for principal diagnosis cases. However, the temporal improvement in sensitivity in coding of MI subtypes, particularly NSTEMI, may necessitate modification to trend studies using administrative hospitalisation data.

Keywords: ICD-10 coding; NSTEMI; STEMI; Validation.

MeSH terms

Australia / epidemiology
Hospitalization
Humans
International Classification of Diseases
Myocardial Infarction* / diagnosis
Myocardial Infarction* / epidemiology
Non-ST Elevated Myocardial Infarction*
Risk Factors
ST Elevation Myocardial Infarction* / diagnosis